I tried different ways to get the dimensioins reverse engineered.

Scan it, import it to inscape and trace the outlines by hand worked somewhat akwardly, because I never got the dpi conversation fitting.

So I now do a mix of get the outer dimensions and sice of teh hole old fashioned with a caliper and used an usb microscope for the dimensions of the connection pads. That seems to work fine:

To my pleasure and suprise it's metric. You see a snap from the microscope which comes with some transparent scaling "thingy". (big lines 1mm, small ones 0.1mm). So I will do some CAD work for the dimension before I dig in the PCB design which I haven't entered before...

Oh, and I#m thinking about to put an optional connector for the thinkpads on the backside and perhaps some holes for standard headers for debugging in the area on the board which can't be populated when used inside the case.